RESUMEN
The aim of this study was to develop nanoemulsion containing soft extract of stem bark of Rapanea ferruginea to improve the topical delivery and anti-inflammatory activity. The extract of R. ferruginea stem bark was incorporated into the oily phase of the nanoemulsion by the method of phase inversion at low energy. The developed nanoemulsion had an average droplet size of 47.88±8.20 nm and a polydispersibility index of 0.228. Uniformity of size, spherical shape of droplet, and absence of clusters were confirmed by transmission electronic microscopy. The zeta potential was -34.7±1.15 mV. The nanoemulsion showed a moderate degree of skin irritation in the agarose overlay assay in vitro. The content of the extract markers, myrsinoic acids A and B, was 54.10±0.08 and 53.03 µg/g in the formulation, respectively. The formulation demonstrated pseudoplastic and thixotropic rheological behavior. In vitro release of chemical markers was controlled by diffusion mechanism. An extract-loaded nanoemulsion showed a topical anti-inflammatory activity in a croton oil-induced edema ear model, with a decrease in tumor necrosis factor release and myeloperoxidase activity. The nanoemulsion was 160% more efficient than the conventional cream containing 0.13% of the extract. The nanoemulsion showed suitable properties as a carrier for topical use of R. ferruginea extract and the approach for improving the topical anti-inflammatory activity.
RESUMEN
ABSTRACT The fruits of Litchi chinensis Sonn., Sapindaceae, are renowned for their biological activities. However, their leaves are poorly explored, although they represent an important source of vegetable raw material with biological properties as antioxidant, anti-inflammatory and antinociceptive. An HPLC method was developed and validated for the simultaneous quantification of epicatechin and procyanidin A2 in the leaf hydroethanolic extract of L. chinensis. The markers and other unidentified components were separated on a Luna Phenomenex C18 column (250 mm × 4.6 mm, 5 µm) with mobile phase composed of acetonitrile: water pH 3.0 (with sulfuric acid), in a gradient run; at 1.0 ml min-1, 30 ºC and 278 nm for detection. The method was linear over an epicatechin and procyanidin A2 concentration range of 10–100 µg ml-1. The Limit of Quantification for epicatechin and procyanidin A2 were 1.7 and 2 µg ml-1, respectively. The Relative Standard Deviation (%) values for markers (intra- and inter-day precision studies) were <4.0% and the accuracy was 100 ± 5%. The method was applied to ten samples collected in the state of Santa Catarina (Brazil), which showed 14.8–44.5 and 44.8–69.6 mg g-1 of epicatechin and procyanidin A2, respectively. The proposed method could be a valuable tool for quality assessment of L. chinenis leaves as well as their herbal derivatives.